I'm using a 2010 Head First Book for Python, chapter 2. I've created a module called nester, which contains the function print_lol, then made another program which should import nester, create a little list, and then call the function print_lol contained in nester. It doesn't work, tho.
import nester
cast = ["Palin", "Cleese", "Idle", "Jones", "Gilliam", "and Chapman."]
nester.print_lol(cast)
This is the program, and this is the output:
> Traceback (most recent call last):
File "<pyshell#2>", line 1, in <module>
nester.print_lol(cast)
AttributeError: module 'nester' has no attribute 'print_lol'
What's wrong with that? Why this happens? The code is exactly as in the book, same path, environment paths are ok. What's wrong?
Here is the 'nester' code, and it works properly.
def print_lol(the_list):
for each_item in the_list:
if isinstance(each_item, list):
print_lol(each_item)
else:
print(each_item)
Also, the nester it's in C:\nester. It contains setup.py, nester.py, and the installation folders and files: MANIFEST, Lib, dist, build.
Try this on your python console
dir("nester")
It should show all the available functions. You might need to make sure print_lol is in the list. Most likely, it is under some other sub-tribute. So the way you call it should be nester.some_tribute.print_lol()
Since import nester didn't throw in error, that means your script can import nester. Try (explicit function import)
from nester import print_lol
If this fails, make sure print_lol exist in nester, as in there are no spelling mistakes.
I guess I found out the answer, and it was pretty easy, but I didn't notice that until deeper research on the website with two friends here.
The module where the 'nester' class is put it's called 'nester'. So when I tried to import 'nester', I imported the module, not the class. I changed the code from the question one to:
from nester import nester
cast = ["Palin", "Cleese", "Idle", "Jones", "Gilliam", "and Chapman."]
nester.print_lol(cast)
So I import from 'nester' Module the 'nester' Class.
Pro-tip: NEVER use the same name for Module and Class.
Credits:
Related
I've seen dozens of questions like this with different problems / solutions. After going through the first dozen or so on StackOverflow, I haven't found a solution to my problem which is:
I have a class like this:
class Flight:
pass
in a file called airtravel.py and then on my REPL (in that directory) I use:
from airtravel import Flight
which immediately fails with:
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ImportError: cannot import name Flight
>>>
Any suggestions?
There is no such library in Python and PyPi - https://pypi.org/search/?q=airtravel
Make sure they are both on the same directory. Your main.py And airtravel.py
There's several reasons this can happen. Since it's not a ModuleNotFoundError I can think of two things you can try:
Make sure you've spelled Flight correctly in both places. If that doesn't solve your problem then
Change the name of the module from airtravel to something else like airtravel2. The reason for this is that there's a possibility that there's another module named airtravel somewhere else, and is being imported because of higher precedence.
You can try below suggestion and see if it helps.
Probably latest content of your file airtravel.py is not Saved.
Try renaming your file airtravel.py to some other name say airtraveltest.py
After I import functools I receive such message from interpreter:
Traceback (most recent call last):
File "C:/Users/Admin/Documents/Python/decorator.py", line 1, in
import functools
File "C:\Python3\lib\functools.py", line 22, in
from types import MappingProxyType
ImportError: cannot import name 'MappingProxyType'
import functools
def trace(func):
def inner(*args, **kwargs):
print(func.__name__, args, kwargs)
return func(*args, **kwargs)
functools.update_wrapper(inner, func)
return inner
#trace
def foo(x):
return x
foo(42)
Using PyCharm as IDE and CPython as interpreter
This is not a real answer, but a comment.
First: I can't verify the problem presented: The code within the question works perfectly in the standard python I am using.
Second: I stumbled upon this question because I had the same error message, but maybe for a different reason. I accidentally named a module "type". Strangely the python framework selected this new "type" module while resolving references from within imported system modules. Which indicates that python's algorithm of resolving references is a bit ... well ... of a bit of very simple design.
Nevertheless if readers get this error message please check first if you accidentally named something "type" somewhere in your code as a first approach to solve the problem before checking other reasons for that error message.
Update: This is a quite common phenomenon in Python. Be careful! Whenever you give your module a name that has already been used for any imported Python module (and you might not be aware of these names!) you will have the chance of getting strange errors more or less similar to the one described in the question.
The accepted solution forces you to rename your module, but:
There's nothing wrong with having a module named types in your package, actually you'll get this error if the interpreter is run with either the current directory or a PYTHONPATH directory is set to the directory containing the module.
If you avoid this situation, you won't have to rename your module.
If you use an IDE, check the run configuration to make sure PYTHONPATH or current directory isn't set to include your modules.
I have a module called imtools.py that contains the following function:
import os
def get_imlist(path):
return[os.path.join(path,f) for f in os.listdir(path) if f.endswith('.jpg')]
When I attempt to call the function get_imlist from the console using import imtools and imtools.get_imlist(path), I receive the following error:
Traceback (most recent call last):
File "<input>", line 1, in <module>
File "C:\...\PycharmProjects\first\imtools.py", line 5, in get_imlist
NameError: name 'os' is not defined
I'm new at Python and I must be missing something simple here, but cannot figure this out. If I define the function at the console it works fine. The specific history of this module script is as follows: initially it was written without the import os statement, then after seeing the error above the import os statement was added to the script and it was re-saved. The same console session was used to run the script before and after saving.
Based on small hints, I'm going to guess that your code didn't originally have the import os line in it but you corrected this in the source and re-imported the file.
The problem is that Python caches modules. If you import more than once, each time you get back the same module - it isn't re-read. The mistake you had when you did the first import will persist.
To re-import the imtools.py file after editing, you must use reload(imtools).
Same problem is with me I am also trying to follow the book of Programming Computer Vision with Python by Jan Erik Solem" [http://programmingcomputervision.com/]. I tried to explore on internet to see the problem but I did not find any valuable solution but I have solved this problem by my own effort.
First you just need to place the 'imtools.py' into the parent folder of where your Python is installed like C:\Python so place the file into that destination and type the following command:
from PIL import Image
from numpy import *
from imtools import *
Instead of typing the code with imtools.get_imlist() you just to remove the imtools from the code like:
get_imlist()
This may solve your problem as I had found my solution by the same technique I used.
I've got a script where I want to import a dict from a file and then use it to execute functions.
The file codes.py is as follows:
rf_433mhz = {
"0x471d5c" : sensor_LaundryDoor,
}
And the file it's using is as follows:
#!/usr/bin/python
import mosquitto
import json
import time
def sensor_LaundryDoor():
print "Laundry Door Opened"
mqttc.publish("actuators", json.dumps(["switch_HallLight", "on"]))
from codes import rf_433mhz
but I'm getting a NameError.
Traceback (most recent call last):
File "sensors.py", line 11, in <module>
from codes import rf_433mhz
File "/root/ha/modules/processing/codes.py", line 2, in <module>
"0x471d5c" : sensor_LaundryDoor,
NameError: name 'sensor_LaundryDoor' is not defined
Is there any way to do what I'm trying to do? It seems to be getting stuck on not having the function inside codes.py
I'm trying to call sensor_LaundryDoor() as follows
def on_message(msg):
inbound = json.loads(msg.payload)
medium = inbound[0]
content = inbound[1]
if str(medium) == "433mhz":
try:
rf_433mhz[str(content)]()
except:
print "Sorry code " + content + " is not setup"
import isn't include. It won't dump the source code of codes.py into your script; rather, it runs codes.py in its own namespace, almost like a separate script, and then assigns either the module object or specific module contents to names in the namespace the import is in. In the namespace of codes.py, there is no sensor_LaundryDoor variable.
The way you're dividing the code into modules isn't very useful. To understand codes.py, you need to understand the other file to know what sensor_LaundryDoor is. To understand the other file, you need to understand codes.py to know what you're importing. This circular dependency would negate most of the benefit of modularizing your code even if it wasn't an error. Reorganize your code to fix the circular dependency, and you'll probably fix the NameError as well.
The problem is that in your dictionary that you're importing, you're setting the value of 0x471d5c to a variable that was either not defined, or not defined in that scope.
An example of this would be like:
Codes.py
#!/usr/bin/python
sensor_LaundryDoor = 'foo'
rf_433mhz = {
"0x471d5c" : sensor_LaundryDoor,
}
Main files
#!/usr/bin/python
from test import rf_433mhz
print rf_433mhz["0x471d5c"]
There are hacky ways to solve this but it looks like the real issue is that you're trying to write C-style code in Python. The Python way to do things would be to import sensor_LaundryDoor in codes.py before using it, and if this introduces a circular reference then that's a design issue.
Maybe you need three modules, events.py with your main loop which imports the dict from codes.py which imports the functions from sensors.py.
I am getting back into python and I'm having a really basic issue....
My source has the following...
def calrounds(rounds):
print rounds
When I run this through the shell and try to call calrounds(3) I get..
Traceback (most recent call last):
File "<pyshell#1>", line 1, in <module>
calrounds(3)
NameError: name 'calrounds' is not defined
Its been awhile since I've used python, humor me.
Did you import your source first?
It says that the first line of your program is calling calrounds with a parameter 3. Move that below your function definition. The definition needs to be before you call the function. If you are using python 3.0+ you need parenthesis for the print statement.
>>> def calrounds(rounds):
print(rounds)
>>> calrounds(3)
3
The first thing to do is to look at how you're calling the function. Assuming it's in myModule.py, did you import myModule or did you from myModule import calrounds? If you used the first one, you need to call it as myModule.calrounds().
Next thing I would do is to make sure that you're restarting your interpreter. If you have imported a module, importing it again will not reload the source, but use what is already in memory.
The next posibility is that you're importing a file other than the one you think you are. You might be in a different directory or loading something from the standard library. After you import myModule you should print myModule.__file__ and see if it is the file you think you're working on. After 20 years of programming, I still find myself doing this about once a year and it's incredibly frustrating.
Finally, there's the chance that Python is just acting up. Next to your myModule.py there will be a myModule.pyc - this is where Python puts the compiled code so it can load modules faster. Normally it's smart enough to tell if your source has been modified but, occassionally, it fails. Delete your .pyc file and restart the interpreter.